A conventional electronic wrench is disclosed in U.S. Pat. No. 3,970,155, and includes a handle and a function end such as a box end or two open-ended jaws, two resistive strain gauges are embedded in the tool and located between the function end and the handle. The two resistive strain gauges are electronically connected to a display window which shows the value of the torque that the wrench applies to objects. However, the value of the torque that is displayed in the display window is not precise enough to meet the practical needs. Another conventional electronic wrench is disclosed in U.S. Pat. No. 4,982,612, and includes a handle and a function end such as a box end or two open-ended jaws. A first resistive strain gauge is disposed in the neck, two second resistive strain gauges are disposed in one of two sides of the neck, and a third resistive strain gauge is disposed in the other side of the neck. The four resistive strain gauges are electronically connected to a Wheastone bridge which is connected to a processor and a display window. By the four resistive strain gauges, the result is more precise. Nevertheless, it is noted that even if the wrench applies the same torque to an object, to rotate the wrench in clockwise and counter clockwise can have two different values form the reading of the display window. This is because one of the two jaws of the wrench bears different force during rotation of the wrench.
The present invention intends to provide an electronic torque applying tool which includes two resistive strain gauges respectively contacting the object to be rotated and the processor of the tool can be set to read either one of the two gauges in pre-set ways to provide the users more precise results.